Push-button snap action switch utilizing a permanent magnet means,particularly for communication equipment



ay 6, 1969 K. SCHMlD-ZELLER ET AL 3,043

PUSH-BUTTON SNAP ACTION SWITCH UTILIZING A PERMANENT MAGNET MEANS, PARTICULARLY FOR COMMUNICATION EQUIPMENT Filed Aug. 28, 1967 1a 5 u, l{1b g, sfigs 1c 1 if 1. S 8 I: 5 La s 9 1.

INVENTORS ATTYS.

United States Patent Office 3,443,043 Patented May 6, 1969 3,443,043 PUSH-BUTTON SNAP ACTION SWITCH UTILIZING A PERMANENT MAGNET MEANS, PARTICU- LARLY FOR COMMUNICATION EQUIPMENT Karl Schmid-Zeller and Heinz Thormann, Munich, Germany, assignors to Siemens Aktiengesellschaft, Munich, Germany, a corporation of Germany Filed Aug. 28, 1967, Ser. No. 663,751 Claims priority, application Germany, Sept. 2, 1966, S 105,666 Int. Cl. H01h 21/06 Int. Cl. 200-67 7 Claims ABSTRACT OF THE DISCLOSURE A push button switch, particularly for communication equipment, having an actuating key structure, an annular body disposed in coaxial relation with respect to the key structure, said body being positioned in a magnetizable housing structure, and movable therein responsive to key movement, with some play therebetween or equally movable therewith, the annular body being constructed as a permanent magnet or having permanent magnet means to provide a magnetic flux, as a result of which the body is retained, in the nonactuated position, engagement with the housing by magnetic adhesion, and axially movable responsive to movement of said key in actuating direction, operative to initially oppose such key movement as a result of such magnetic adhesion, and upon the release thereof, to effect a quick break movement and contact actuation in response to the magnetic flux concentration in the area of its final actuated position.

The invention relates to key switches particularly suitable as push-button switches for communication equipment.

It is the problem of the present invention to produce a simple push-button switch with a snap-action characteristic which, in particular, is suitable for the operation of protective gas contact arrangements. In a switch according to the invention, there is disposed in coaxial relation with respect to the actuating key structure, an annular body which is positioned in a magnetizable housing structure, and movable therein responsive to key movement, with some play therebetween or equally movable therewith, the annular body being constructed as a permanent magnet or having permanent magnet means to provide a magnetic flux, as a result of which the body is retained, in the nonactuated position, in engagement with the housing by magnetic adhesion, and axially movable responsive to movement of said key in actuating direction, operative to initially oppose such key movement as a result of such magnetic adhesion, and upon the release thereof, to efl'ect a quick break movement and contact actuation in response to the magnetic flux concentration in the area of its final actuated position. Thus, a snap-action characteristic can be achieved resembling an over center spring arrangement.

In a preferred embodiment of the invention, such annular body is constructed as a radially magnetized permanent magnet toroidal core.

Particularly favorable conditions suitable for the operation of scaled contact arrangements arise in connection with push-button switches, i.e. push-buttons in which for the duration of the key actuation a switch is to be closed, which of course can also incorporate switch-over contact arrangements. According to a development of the invention, this can be accomplished by the use of a currentcarrying magnetizable pin coaxially disposed to the pushbutton, which is rigidly mounted in and electrically insulated from a carrier plate constituting a component part of the housing, with the pin extending at a right angle thereto with its end facing away from the push-button constituting a contact member. Such contact member is cooperable with an oppositely disposed movable contact member which is electrically and magnetically connected to the housing. The annular body, in the form of a radially magnetized permanent magnet toroidal core, in the rest position of the key is urged by a compression spring surrounding the pin into engagement with a shoulder on the housing, enclosing the nonmagnetic neck of the pushbutton, while upon actuation of the key, following the initial movement, the switch is closed by the actuating force derived from magnetic attraction between the permanent magnet core and an oppositely disposed stop for the ring located relatively closer to the pin than the shoulder and constituting a part of the key structure or of the housing, as a result of magnetic flux concentration in the movable contact piece.

Further details of the invention will be apparent from the embodiment illustrated in the drawing, in which:

FIG. 1 is a cross section of a push-button switch according to the invention, illustrated in rest position;

FIG. 2 is a cross section of the switch according to FIG. 1, illustrated in operating position; and

FIG. 3 is a top plan view of the permanent magnet utilized.

A push-button switch according to the invention for communication purposes, and if desired also for the control of electric typewriters and the like, comprises a key body 2 disposed in a housing 1 of magnetic material, the key body in turn comprising a flange-like actuating button 2a, having a nonmagnetic cylindrical neck portion 2b which extends into a flanged opening or boss 1a of the housing, a still thinner stern portion 20, and a cylindrical flange member 2d connected thereto, whose outer diameter approaches the inner diameter of the principal portion 1b of the housing. In the rest position, illustrated in FIG. 1, the key structure 2 and the housing substantially completely enclose an annularly-shaped permanent magnetic body 3 which, as illustrated in FIG. 3, is radially magnetized.

The housing member 1b which is open at the bottom is supported preferably without open joints, on a likewise magnetizable, substantially cylindrical, sealed protective gas container 4, through the top wall 4a, of which extends a magnetizable pin 5 insulated by means of a glass seal 7, which forms a fixed contact member of a protective gas contact arrangement. A flexible spring member 6 which is both electrically and magnetically conductive, serves as a cooperable contact member, which is conductively connected to the container 4. Pin 5 is suitably electrically connected to a connection member (not illustrated) which is insulated from the housing or the container, as the case may be. A compression spring 8 disposed between key part 2d and a nonmagnetic annularly-shaped filler block 9 dis-posed on the top wall 4a of the protective gas container normally maintains the key body in the rest position, illustrated in FIG. 1, in which position the magnetic body 3 is attracted and adheres to surface 10 of housing 1, with only a small secondary magnetic flux running over pin 5 and container 4. Upon downward pressure on key structure 2, in opposition to the force of return spring 8, after distance s has been traveled the magnetic adhesion force creates additional resistance to such key movement. Upon further pressure on the key, the shoulder thereof pushes down on magnet 3 breaking the adhesion with surface 10, moving it toward the flux guiding pin 5. When the point of equilibrium is passed beyond which the flux guiding pin attracts the magnet, the latter flies, independently of further key movement, until it reaches the stop formed by the flange 2d. Since the flux guiding pin 5 now extends into the annular magnet, the flux in the magnetic circuit closed thereabove is sufficiently concentrated (see FIG. 2) that it reaches the value necessary to close contacts 5-6. Upon release of key button 2a, the key structure and therewith the annular magnet 3 are returned into their initial rest positions by means of return spring 8, thereby again opening the contacts. Since the adhesion force of the permanent magnet is dependent upon the size of the adhesion surface, as well as on the magnetization of the magnet, the key pressure can be varied through corresponding dimensioning of these two factors without thereby afiecting the switching operation of the contacts.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.

We claim:

1. A push-button switch, particularly for communication equipment, comprising a housing structure which is at least partially ferromagnetic, an actuating key structure, an annular body disposed in coaxial relation with respect to said actuating key structure, said annular body being positioned in said housing structure and movable therein responsive to key movement relative to the latter, the annular body being constructed to provide a magnetic flux as a result of which the body, in its nonactuated position, is retained in engagement with the housing by magnetic adhesion, and axially movable responsive to movement of said key in actuating direction, said annular member being operative to initially oppose such key movement as a result of such magnetic adhesion, and magnetically actuatable contact means cooperable with said body, the latter being operable upon release of said magnetic adhesion responsive to key actuation to effect a snap-action type of movement and effect contact actuation in response to the magnetic flux concentration in the areal of its actuated position.

2. A push-button switch, according to claim 1, wherein said annular body and key structure are so constructed that an amount of play exists therebetween.

3. A push-button switch according to claim 1, wherein the annular body is constructed as a radially magnetized permanent magnet toroidal core.

4. A push-button switch according to claim 3, wherein said magnetically actuatable contact means comprises a .4 contact member in the form of a rigidly disposed ferromagnetic pin coaxially positioned with respect to said key structure, mounted in electrically insulated relation in a member forming a part of the housing structure, a cooperiable moveable contact member electrically and magnetically connected to the housing, said housing having a shoulder engageable with said body when in nonactuated position, a compression spring surrounding said pin and operative to urge said key structure in nonactuated position and the body into engagement with said shoulder, said pin and body being cooperable in actuated position to effeet a magnetic flux concentration in the area of said movable contact member to eliect actuation thereof.

5. A push-button switch according to claim 4, wherein said key structure is provided with means provided at the inner end thereof forming a stop for said annular body which defines the actuated position of the body.

6. A push-button switch, according to claim 4, wherein said annular body and key structure are so constructed that an amount of play exists therebetween, said play being such that the key structure upon being actuated effects an initial movement before engaging the permanent magnet body.

7. A push-button switch according to claim 4, wherein the end of the pin remote from the contact end thereof, upon actuation of the switch, extends sufiiciently into the permanent magnet annular body.

References Cited UNITED STATES PATENTS 2,637,115 5/1953 Watson.

3,175,060 3/ 1965 Crissinger et a1 335-205 3,273,091 9/1966 Wales.

3,292,123 12/ 1966 Siklos 335205 3,373,386 3/1968 Ehrenberg 335-205 ROBERT K. SCHAEFER, Primary Examiner. H. BURKS, Assisfalnt Examiner.

US. Cl. X.R. 3 3 5-205 

